Drive against vibrations - active vibration isolation for building technology systems

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© Fraunhofer IBP

Noise control is not only a device against ear-deafening noise. Even background noise, which is influencing recovery, sleep and concentrated work, must be reduced. An especially interfering group of noise sources in buildings are building technology systems and installations, e.g. ventilation and heating systems, elevators and a multitude of water and sanitary installations. Besides noise in the vicinity they generate vibrations, which are propagated as structure-borne sound in the building, and finally reflected as audible sounds from the walls of adjacent rooms.

So far, flexible fixing and supports were generally used as remedial measure, but only a minor effect could be achieved in case of low frequencies. The problem, however, is exactly low-frequency humming and booming as an audible result.

Therefore, an active system was developed to isolate low-frequency structure-borne sound. This cost-efficient system, which is simple regarding the control technology, constists of a vibration sensor and a vibration acutator linked by an electronic module (signal processing and amplification) and coupled to the vibrating structure. Thus, the transmission of low-fequency vibrations from installations and equipment into the building can be already considerably reduced at the point of introduction. At the same time, an adjusted combination with passive measures is possible without any problems.

Measurement and audibility results show that this active system is predominantly effective in the frequency range between 63 and 400 Hz. The combination of passive and active vibration reduction even achieves a broadband noise reduction in the total range of human audibility. In view of the resulting gain in living comfort and quality of life present developments focus on the optimization of the relation of costs and benefit, whereby this does not only mean the costs per dB noise reduction. The focus is also the technical integration in the building structure, which is to save as much weight and space as possible, be it a new building or a building to be renovated .